Automatic radio signaling means for aviation trainers



Feb. 1, 1949. G G 2,460,511

AUTOMATIC RADIb SIGNALING MEANS FOR AVIATION TRAINERS Filed May 27, 1945 s Sheets-Sheet 1 GREGOR L.LANG

INVENTOR. AflM/Ww MW.

ATTORNEYS.

Feb. 1, 1-949. G. LANG AUTOMATIC RADIO SIGNALING MEANS FOR AVIATION TRAINERS 3 Sheets-Sheet 2 Filed May 27, 1945 FIG. 6

GREGOR' L. LANG INVENTOR. B7 WM ATTORNEYS.

Feb. 1, 1949.

Filed May 27, 1943 G. L LANG AUTOMATIC RADIO SIGNALING MEANS FOR AVIATION TRAINERS 3 Sheets-Sheet 3 4s 94 I22 I24 70 E C Q 50 AH. I34 ea LT! |l' l26 I36 so :I4o 54 I 5 66 as I40 75 I2a 64 i =3 67 so I40 FIG. 4

GREGOR L. ANG INVENTOR.

ATTORNEYS Patented Feb. 1, 1949 AUTOMATIC RADIO SIGNALING MEANS FOR AVIATION TRAINERS Gregor L. Lang, West Haven, Conn., assignor to Link Aviation, Inc., a corporation of New York Application May 27, 1943, Serial No. 488,659

3 Claims.

My invention relates to an aviation trainer,

and particularly to means for training pilots in the art of navigation by radio.

Radio aids have proved to be of great and increasing value to the navigator. Among the most important of these radio aids are the signals sent out by those stations commonly referred to as radio range stations. Each radio range station transmits a pattern marking four courses, normally 90 apart, although this spacing is often varied in order that one or more of the courses will coincide with an established airway. This system utilizes generally two pairs of transmitting towers which transmit interlocking Morse code signals. For instance, one pair of towers may be transmitting directionally the letter A while the other pair transmits the letter N the timing being synchronized so that at all times one pair of towers is transmitting a signal.

This arrangement produces the result that in any two diagonally opposite quadrants, as seen in Fig. 1, the A signal is heard clearly and the N signal is of a lesser intensity or is not heard at all, depending upon how far the plane is from an N quadrant. In the other pair of diagonally opposite quadrants, the relative intensities of the letters are reversed. Each quadrant slightly overlaps the neighboring ones and in the narrow Wedge of about 3 that forms the center of the overlap, the A and N signals are heard with equal intensity so the dots and dashes of the two signals' interlock to produce a continuous tone. This is the familarly on-course signal.

The navigator of a plane, by intercepting the signals being transmitted by such a radio range station will therefore be able to tell whether the plane is in an A quadrant, an N quadrant or on one of the on-course beams. By maneuvering the plane and noticing the efiects of the maneuvers upon the intercepted signals the pilot is able to locate the position of the plane in the radiated field pattern of the radio range station and, inasmuch as he has in the plane with him a map of the emanated field pattern of the station, he can ascertain the geographical position of the ship. A concrete detailed example of exactly how this is accomplished is set forth in my copending application Serial No. 440,950, since matured into Patent No. 2,435,502, dated February 3,1948.

In the instruction of students to fly by means of the signals transmitted by these radio range stations it has been found particularly desirable to combine with a trainer of the type disclosed in U. S. Patents 1,825,462 and 2,099,857, which trainers are commonly known as Link trainers, means whereby simulated radio signals may be transmitted to the student in the trainer who, by interpreting the simulated signals received, navigates the trainer in the same manner that he would actually navigate a real plane by means of actual radio range signals.

It is common practice in the prior art to combine with such a trainer a recorder of the type disclosed in U. S. Patent 2,179,663, which recorder is placed upon a map of a real or imaginary radio range station signal field. This recorder responds directionally to the changes in the heading of the trainer so that it travels at all times over the map in the same direction as the trainer is assumed to be flying through the radio range signal field. The student in the trainer controls the direction of the trainer and, therefore, the direction of the recorders travel, in response to the simulated radio range signals received :by him, and the recorder traces the assumed track of the trainer through the assumed radio range signal field. The instructor in turn transmits signals to the student in the trainer in accordance with the observed position of the recorder upon the map, which position represents the assumed position of the trainer in an assumed radio range signal pattern.

Means under the manual control of the instructor whereby he can transmit A-N signals of varying relative intensities and of varying absolute intensities to the student in the trainer in accordance with the moving position of the recorder over the map are disclosed in my copending application Serial No, 440,950, as well as U. S. Patent 2,119,083. However, such a system has several disadvantages. First, such a system requires the constant close attention of the instructor. Secondly, the instructor at all times must estimate the desired relative intensities of the A-N signals as well as the proper absolute volume to be given these signals, and then he must manually set the controls in the positions which he believes will give the estimated desired signal intensities. In order that the constant attention of an experienced instructor may be dispensed with, and in order to eliminate the inevitable errors of judgment upon the part of the instructor, it is highly desirable that there be automatic means for changing the relative as well as absolute intensities of these A-N signals heard by the student in the trainer as the recorder changes its position upon the map. It is a principal object of my invention, as well as of my invention disclosed in my abandoned application Serial No. 483,431, filed April 17, 1943, to provide means which will replace the manual controls :by which the instructor determines the relative as well as absolute A and N signals transmitted to the trainer by a fully automatic device which will transmit to the student signals more nearly simulating the signals whicha plane would intercept if it were actually flying the flight that the trainer is assumed to be making.

It is a further object of my invention to pr vide such a means eliminating the use of radio frequencies. It is a complementary object of my invention to provide an automatic radio range comprising the use of audio frequencies only.

It is a further object of my invention to combine the foregoing objects with a range utilizing an electrostatic field of an alternating audio-frequency current keyed in accordance with the conventional Morse code signals for the letters A and N.

It'is still a further object of my invention to provide a miniature automatic radio range utilizing a'plurality of metallic quadrants to form an electrostatic field of an alternating audio frequency current keyed in accordance with the conventional Morse code signals for the letters A and N.

It is another object of my invention to provide means whereby bent courses, multiple courses and other irregularities in the emanated field pattern of a 'radio range station may be simulated 'in an automatic radio range of the type provided by this invention.

The preferred embodiment of my invention is shown in'the accompanying figures in which like reference numerals indicate like parts. In the figures,

Fig. 1 is a general view showing the trainer, desk, map andrecorder.

Fig. 2 is a front elevati-on of certain parts of my automatic radio range.

"Figs. 3 and 4 show the electrical circuits .of

such a range.

Fig. 5 is a detailed view of the signal pickup means and associated parts.

Fig. 6 is a cross sectional view of two of .the

quadrants of my invention, taken on the line VI--V-I of Fig. 2.

In Fig. 1, the numeral m designates a trainer of the type previously mentioned, and the-trainer is electricallyconnected to the various parts located at the instructors desk l2 by means of cable l4. Upon the desk 52 is map is which shows the radiated field pattern of a real or assumed radio range station, and placed upon the map is the recorder designated generally as I8. The functioning of this recorder .has been previously described. Referring now to Fig. 2 .it will be seen that therecorder I8 rests upon the top 20 of the desk and thistop is preferably made of an insulating materialsuch as wood, Bakelite,-or glass. Map [6 is not shown in this view. Supporting member26 is suitably attached to .desk l2 and four quadrant-shaped sheets-of metal-28, 3U, 32 and 3-4 rest upon member 26 and are arranged to apparently form a largedisc whenseen from above as ..in.Fig. 3. Only three of these quadrants 28, 3B, and 34 are shown in Fig. 2. These quadrants .areall insulated from one another as seen in Fig. 3 by wedge-shaped open.- ings 21. These quadrants slope downwardly .toward their peripheries, and the central part-of each'of these quadrants is closest to the table .ible arm 5- top 28. The edges of each of the quadrants along wedge openings 21 also slope downwardly, for purposes to be hereinafter explained. It will be seen that a plurality :of cables designated generally in Fig. 2 by 36 are suspended below member The function of these cables will also be later described. These quadrants form the stator electrodes and their spacing, formeand relative positionsdetermine the fconfigurationoi the resulting electrostatic space field, as will also be later understood.

Reference is now made to Fig. 3 which shows 'mypref-erredelectrical system. As seen in this figure, there is provided an oscillator 38 which generates a 1020 cycle tone. This frequency is preferably used in my invention because the modulating frequency used by radio ranges are of this sameirequency. By means of conductors 38 a 1020 cycle wave will be set up in the series connected primaries 42 and 44 of the transformers designatedgenerally by lia-M48. similar tone will therefore be induced in .the secondaries ductors .59 .and H.

The quadrantstiiiandfid, beingconnected to pppositeends of the .samesecondary, will beinstantaneously charged .at equal and opposite voltages. In other words their voltages are outer-phase. iffiexiblearmtllbeout of contact with flexible arm 68, as shown in Fig. 3,

quadrant .38 will be electricallycharged, and if flexible arm 54 be out-of: contact-with flexible arm 6?, also as seen in Fig. 3, quadrant 34-also will be charged. Blocks .-1:5 .in which these flexible contact armsare mounted are IlOI'k-ECOIldllCtOIS. Quadrant 36 will have'the same polarity asthe end of the secondary -.52-to which it is connected and-quadrants; will have the same-polarity .as the other end of-secondarya52. Inasmuchas the polarity of this secondarychanges in' aecordance with the frequency ofsignal source 38 the polaritiesof quadrants 30 and 34=will"change at the same rate, in the event flexible arms-6 6 and '6"! are ,positioned as shown-in Fig. 3. A1020 cycle voltagewilhthereforerbe induced in each :of these quadrants. However in the eventthat contact arm to bein contact with armifiejquadrant 30 .will not become charged because 'it is connected to groundfie which, it'is to be noticed, is 'connectedto center tap l2-of-secondaryi52 by'm-eans of conductors 'l'it'ancl 1B, thereby completing'the circuit. Also, 'if flexible "-arm 54 be in .contact with flexible arm 61, quadrant $4 will :not become charged -for #the same reason. :Further- 1nore,'when arm-66 contactsarm 6e and arm'i'l contactsarm Bkquadrantstlland s' iiare shorted by 'means of-conductor I28, andtherefore, no charge placeduponrthese quadrants. As will hereinafter be: explained, the=p:osition of rotation of A-N cam in governs the -making and breaking of the above-'mentionedlcontacts.and,therefore, also 1 governs the charging of the quadrants 3i! (and 34.

Still referring to Fig. 3, it is to be noted-that the .left end of secondary :50 is connected to quadrant 3-2 by 'meansrofeonductor 18 and-this quadrant is connected tmflexibleaarm-Btlby means of conductor '82. Similarly, 'the -*right end of the event flexible member 80 is in engagement with flexible arm 61, as shown in Fig. 3, no charge will be placed upon quadrant 32 because it is shorted to quadrant 28 and is connected to ground 68 and by means of conductors 16 and 90 to the center tap 92 of secondary 50. In the event fiexible member 86 is in engagment with flexible arm 56, also as shown in Fig. 3, no charge will be placed upon quadrant 28- However, if contact 86 were out of engagement with arm 66, and contact 88 were out of engagement with arm 61, quadrants 28 and 32 would be charged in accordance with the polarities of the end of secondary 58 to which they are connected. Inasmuch as the polarity of secondary 50 changes 1020 times per second, it will be realized that whenever quadrants 28 and 32 are not grounded nor shorted the polarity of the charges placed thereupon will vary at the same rate.

From the foregoing, it will be realized that each of the secondaries 50 and 52 will charge the pair of quadrants connected to it with a 1020 cycle voltage if the quadrants are not grounded and shorted. Each of the quadrants acts as a stator electrode and sets up about it an electrostatic field having the same frequency as the oscillator 38.

A-N cam I8 is rotated in the direction of the arrow as seen in Fig. 3 by any suitable constant speed means such as a small motor (not shown).

The periphery of this cam has a short elevated portion 92, a short depressed portion 96, a long elevated portion 94 and a depressed portion 98 of equal length. Whenever cam I8 is in a position of rotation such that follower I22 rides upon elevated portion 92, the circuit is made at the point I24 and relay I26 is energized. The energization of this relay attracts member I28 toward it and, therefore, flexible contacts 66 and 61 move in the same direction. As long as relay I26 remains energized, contact is made between flexible contacts 66 and 66 on the one hand and contacts 54 and '5! on the other. Therefore, quadrants 28 and 32 are not shorted nor grounded and they will be charged in accordance with the polarity of the end of the secondary 50 to which each is connected. For the length of time that this condition prevails quadrants 38 and 34 are not only grounded but are short circuited by means of member I28, and, therefore, they are at ground potential. Whenever follower I22 rests upon elevated portion 94, the samecondition prevails.

However, in the event follower I22 is within depressed portions 93 or 98 relay I26 will not be energized and member I28 and consequently flexible contacts 56 and 61 will be in their normal positions as seen in Fig. 3. In such position, flexible member 66 is in contact with member 86 and flexible contact 61 is in contact with member 80. When this condition prevails, quadrants 28 and 32 will be grounded as well as short circuited, and, therefore, no charge will be placed thereupon. However, quadrants 30 and 34 will not be grounded and, therefore, will be charged in accordance with the polarity of the end of secondary 52 to which each is connected. Consequently, whenever follower I22 is in depressed portions 93 or 98, the polarity of quadrants 30 and 34 with respect to ground changes at the rate of 1020 times per second, but quadrants 28 and 32 are at ground potential. 'But for the period of time when follower I22 rests upon elevated portion 92 or 94 the polarity of quadrants :28 and 32 with respect to ground changes at the rate of 1020 cycles per second while quadrants 38 and 34 are at ground potential.

Whenever either pair of diagonally opposed quadrants is charged, which, as explained, de-

pends upon the position in rotation of cam 12,

an electrostatic field having the same frequency as signal source 38 is set up in the space adjacent the charged, quadrants.

The Morse code signal for the letter A is a dot followed by a dash while the Morse code signal for the letter N is a dash followed by dot When cam ID is rotated counterclockwise, as seen in Fig. 3, and follower I22 rests upon the elevated portion 92 of cam 73, quadrants 39 and 34 will be grounded as well as short circuited to each other and, therefore, not charged while quadrants 28 and 32 will not be grounded nor shorted and, therefore, will be charged. As the cam moves to such position that follower I22 is in the depression 98 the opposite condition will prevail, namely, quadrants 28 and 32 will be grounded as well as shorted to each other and, therefore, not charged while quadrants 30 and 34 will not be grounded nor shorted and, consequently, will be charged. As cam I0 rotates and follower I22 rests upon the elevated portion 94, quadrants 30 and 34 will be grounded and shorted while quadrants 28 and 32 will be charged. Finally, as cam 78 rotates and follower I22 is in depression 93, quadrants 28 and 32 will be grounded and shorted and quadrants 30 and 34 charged.

It will be realized, therefore, that the rotation of cam I0 causes quadrants 30 and 34 on the one hand and quadrants 28 and 32 on the other hand to become alternately charged positively and negatively for a period of time followed by a remaining at ground potential for a period of time. While one pair of quadrants is being alternately charged, the other pair is grounded and shorted and, therefore, at ground potential. Specifically, from the preceding discussion, it will be realized that quadrants 28 and 32 will be alternately charged for a short length of time, grounded and shorted for a short length of time, then charged for a longerlength of time, followed by a grounding and shorting for a longer length of time, and then the cycle is repeated. Consequently, quadrants 28 and 32 are lternately charged in accordance with the Morse code signal pattern for the letter A and these two quadrants are therefore referred to as the A quadrants. It will also be realized from the preceding discussion that quadrants 39 and 34 will be alternately charged for a long length of time followed by a grounding and shorting for a short length of time and then will be alternately charged for a short period followed by a grounding and shorting for a long period. Therefore, inasmuch as these two quadrants are charged in accordance with the Morse code signal pattern for the letter N they are referred to as the N quadrants. The result realized, therefore, is that the electrostatic field set up by one pair of quadrants (28 and 32) is keyed in the Morse code pattern for the letter A, while the electrostatic field set up by the other pair is keyed in the Morse code pattern for the letter N.

Reference is again made to Fig. 2 which shows the recorder I8 and its inking wheel I30 which traces upon the map It the simulated track of the with the plate circuit.

ure by I32. Reference is now made to Fig- 5 which shows'the detailed arrangement of this part of the invention. In Fig. 5, it will beseen that the electrostatic pick up plate IIJIJ isparallel with'the V top the desk20 and that it isintegrally connected with conductor I02. Suitable insulatingsmaterial f I03 surrounds this conductor and thednsulateci :conductor is covered with metal shielding "I05. A

fiber washer I! is placed above-pickupplate I00 and metal shield cup I09 surrounds the washer and pickup plate and is connected tosthe'shielding I05. Cup 509 is suitably supported-from the recorder by means of bracket I and tube 'II3 formed integrally with cup I09. The recorder l'8, -metal shield cup I09 and metal shielding-I are grounded. Cup I09 and shielding I05 confine the effective capacitive picku elements "to'ele'ctrode 100.

Reference is now made to Fig. '4 which's'hows :the capacitive pickup plate or receiving electrode I00 and the conductor I02 which'isconne'ctedito the control grid I04 of amplifier designated-generally by I06. Variable resistance I05 is inserted between pickup electrode I00 and grid I04 and grid I04 and ground 68. nected to the'direct current. power supply. I Hand The plate -'IIO is conthe primary 1 I4 of a transformer .I I6 is in series Secondar H8 of this transformer is in series with earphones 120.

As the'recorder I8 traces the simulated 'fiight of the trainer I0 over the map 16 0f the radio rangestation, as seen in Fig. 1, the pickup electrode I00 will change its position with respect to the A and N quadrants which areunderithe top 20 of the desk. It will be recalled rthatithe quadrants 30 and 34 are alternately-eharged by the l020'cycle wave intheapattern of :the Mo-rse code signal for the letter N =Whenrecorder .I8 is positioned so that pickup mechanism I332, which includes pickup electrode [100, is in:either of the keyed electrostatic fields sset up .by tthese quadrants, a signal will beimpressedmpon elec- I trode I00 by the electrostatic signal fieldand-Will be transferred by means of con'ductor lmito control grid I04. The'bias of this gri'd will there- "fore be varied at the frequency-of the electrostatic field. The changing bias-of control grid I04 in turn will change'the plate-current'-'of'amp'lifier I06 in the usual manner at "the 'same'frequency, and in the N pattern, and by means of transformer I I6 and N signal will be heard in the earphones I 20.

When the recorder IB'and pickup electrode=I00 is over one of the A quadrants 28-or 32, by-virtue .of corresponding functioning, theMorsecode-signal for the letter A will behearddnthe earphones 20.

Assuming that pickup electrode I00 is aboveth'e bisector of one-of the N quadrants and therefore, in the bisector of the electrostatic'fie'ld set upby that quadrant, the electrostatic fields set up by the A'quadrants will not affect grid I04,'-and consequently, a pure N signal will beheard'by the student, but as the recorder moves in a direction to carry pickup electrode I00 into the *electrostatic field set up by the A quadrantsj the A signal will begin to be heard-but the -signal=will be the louder. If the pickup electrode I00'goes closer to the area above the A quadrants, the intensity of the A signal heard'becomes'greatenuntiLwhen the ickup electrode is above one of the wedgesz'l,

the A andN signals-will merge into-a continuou's tone, in simulation o'f' the en-course note intercepted by a plane in actualflight. In order that 'this note may be continuous; the switches in Fig. 3 operated *by =relay 126 should be of the =ma'kebe'fore breaktype. ScreWs I40 are thereprovide'd in: order"- that exact f timing I of these switches may be--accompli-shed.') :Should the pickup electrode III'O be carried by the recorder-I8 to the areaabove one a'of =the :ZA- quadrants, the A signal would :be heardlouder by the student while the Nsignal *Wlllbe c'f lesser 'intensity, and when the electrode fi00 is completely outof'the area of influenceof theifield's set up by-the N quadrantsgth'e Asignal only will :be heard. It i will, therefore, the realized thati-the-relativeintensities:of the A andN signals heard by :the :student using earphones .are automaticallyvaried as the-recorder I'B carrying electrode E IT00 moves over the map EI 6 of. the .radio man-gestation, lin' simulation of the varying of ethe relative int-ensitiesof the =Aand 2N signals as a plane :in :actual flight flies through .the :radiated field pattern of'a-radio range station.

In actual flight throughia radio :rangesignal zpatternznot only .do -therelative intensities of .the AA and 3N :-signal.s ".vary, depending upon :whether 1 the plane iis .in .an 'A or an :N :quadrant, ibut the absolute volume of lthese signals -.in- :creases as ithe :plane zapproaches the transmit- 'tingstation. In order that this phenomenasmay be simulated by my inven'tion, .-'the IA and 'N quadrants, as seen in Figs. 1, 2 and 5.slope downvwariily .from .their centers so that :their outer :porti'ons are fartherzfrom the .top :20 of t the desk I2. :It will therefore be realized that when the recorder F8 is positioned :upon the map "I6 '50 lthat :the ip-ickupa'electro'de II00 is :at a point :far removed iromrthe center of the quadrants, the electrostatic fiel'd in wvhich :the pickup electrode I00 zwill: be:placed will be relatively weaker because electrode 400 is a greater 'distance from the-quadrants, the bias :of grid I04 will=not be affected :to such -a great extent and, there'fore, l the intensitiespf the-signals heard will be less. Astherecorder moves 'so thatpickup electrode I00 moves toward the simulated transmitting tower, the pickup electrode 200 anoves closer to the =A and N 'quadrants and, therefore, is in a stronger electrostatic 'field and the intensities of the signals 'heard will increaseln other words, 'theactu-al distance between pickup electrode 000 and any of the quadrants determines the ef- "fective capacity of the pickup plate and the quadrant, the smaller the distance the higher the capacity. The value of this-capacity determines'the-amplitude"of the-signal transferred to the -grid I04 by that quadrant, thereby controlling the volume of the signal heard-inthe earphones as-a result ofthe-electrode I0-0-being in the electrostatic field set up by that quadrant.

-As a plane in actual flight through a radio range signal pattern approaches the station from '--a;dist-anc-e, a gradual increase in the intensity of the intercepted signals is observed until theplane'isa short distance from the transner inverse to that experienced upon approaching the cone. As seen in Fig. there is attached to each of the quadrant plates at or close to their inner points a piece of wire or rod I42 which projects upward through the table top so as to nearly touch the pickup electrode I00 as it passes over them. This results in a stronger electrostatic field in the area above these pieces I42 and, therefore, when pickup electrode I00 is in this increased field an intensified signal in simulation of the intensified signal received in actual flight as the plane approaches the transmitting towers is received by the student in the trainer. When the pickup electrode I00 is directly above the center of the quadrants the effects of the opposite polarities or phase opposition of the two charged quadrants cancel each other and no signal is intercepted, in simulation of the cone of silence. The arrangement of pieces I42 has the added advantage of giving a sharply defined signal cancellation zone in simulation of the cone of silence. Therefore, my

invention provides means for simulating the build-up of signals and the cone of silence which are intercepted as a plane flies over the transmitting station in actual flight.

As a plane in actual flight gets relatively close to the equi-signal zones between the A and N quadrants of a real radio range signal field, the absolute intensities of the signals decrease somewhat, even though the distance from the transmitting station is no greater. In order that this effect may be simulated in my invention, as stated earlier in the description, the edges of the quardants along wedge openings 21 slope downwardly, as seen-in Fig. 6. The strength of the electrostatic fields through which pickup electrode 00 passes above the areas 2'! will be weaker and, therefore, grid I04 will not have such a strong signal impressed' thereon for a given distance from the center of the quadrants, and the signals heard in earphones II8 will be correspondingly less intense.

From the foregoing it will be seen that by means of my invention the absolute intensities of simulated radio range signals may be automatically varied with changes in the assumed position of the trainer in an assumed radio range signal field, in close simulation of the varying of signals intercepted by a real plane flying through a real radio range field pattern.

The signal intensities of signals intercepted can be modified by changing the slope of the quadrant plates and any real radio range may be simulated by changing the relative sizes of any of the four quadrants.

As seen in Fig. 3, a variable condenser I34 is connected by means of conductor I 36 to quadrant 34 and the other side of this condenser is connected to ground 68. This arrangement, which is also employed in connection with each of the other quadrants, makes it possible to vary the amount of charge placed upon any of the quadrants. As the charge upon any quadrant is increased or decreased by a manipulation of these variable condensers, the strength of the electrostatic field set up by the quadrant also increases or decreases, and the signal heard by the student in the trainer will be correspondingly increased or decreased. It is therefore possible by means of these condensers to vary the relative intensities of the signals picked up from any quadrant, thereby causing a shift of the four wedge-shaped areas above the quadrants where the A and, N signals are heard with equal intensity. In other words the simulated oncourse beams may be shifted. This arrangement is advantageous because it makes possible the simulation of many diiferent real radio ranges without a physical changing of the A and N quadrants. The same result could be realized by changing the actual shape of the quadrants.

Generally, real radio ranges set up signal patterns as previously described, but in certain parts of the country multiple courses are found, that is, the equi-signal zone, which is normally about 3 in width, is broken up into more than one on-course band. Fig. 5 discloses means for simulating this feature of the real radio ranges, and as seen in that figure, a shielded cable I44 is attached to quadrant 30 at the point I46 which is on the lower side of quadrant 30. This shielded cable runs below quadrant 30, below the wedgeshaped openin separating quadrant 30 and quadrant 28, below quadrant 28 and up through an insulating plug I48. Metallic member I50 is held in separation from quadrant 28 by means of insulating plug I68 and points toward the center of the quadrants as shown. Inasmuch as metallic member I 50 is connected to quadrant 30, it will be realized that'it will setup an electrostatic field synchronized with the field set up by quadrant 30. Quadrant 30, it will be recalled, is an N quadrant and inasmuch as quadrant 28 is an A quadrant, an N electrostatic field will be set up in the midst of the A electrostatic field set up by quadrant 28. When the recorder is above member I50, both the electrostatic field set up by member I50 and the electrostatic field set up by quadrant 28 will be picked up by electrode I00 and, therefore, the student in the trainer will intercept the oncourse signal. To either side of member I50,

however, the A signal from quadrant 28 will preit will be realized that two equi-signal zones are present, thereby simulating the multiple courses which occur in real radio ranges.

Another difiiculty encountered in actual flight is that of the bent equi-signal zones. This phenomenon of actual flight may be simulated in my invention by changing the shapes of the quadrants. As seen in Fig. 5, quadrant 28 has an integralextension I 52 while a corresponding portion i5 3 of quadrant 34 is cut away. It will be readily understood that this arrangement will cause a bend in the equi-signal zone above quadrants 28 and 34.

The previously-mentioned variable resistance I05 shown in Fig. 4 is under the control of the student using earphones I20 and a turning of the volume control of the radio receiver afiects the volume of the signals heard in earphones I20 in the usual manner.

A reference to Fig. 2 will show that the inking wheel I30 of the recorder and the pickup electrode I 00 are not coincident but are a certain distance apart. The position of the inking wheel upon the map designates the exact simulated position of the trainer. Inasmuch as the pickup electrode is separated from the inking wheel it is clear that the map of the simulated radio range and the quadrant plates must be displaced by an amount equal to the distance between the inking wheel and pickup electrode I00. Otherwise the signals intercepted will not correspond with the position of the inking wheel on the map. By

placing :thepickupelectrode 58G exactly above the centeroi=thc-lourquadrant plates and arranging the= map s o; that each of'the on-course beams marked: thereupon areparallel to the wedge shaped openings between the quadrant plates, the:

inkin'gavlieel I Miofthe recorder being placedup on-tlie-intersecting pointof the on-course beams, as outlined' on the map; the mapxandquadrant plates will be correctly oriented, This relationshiphaving been established; the recorder will-be correctly placed at anypoint upon themap ifay;

, Itxwillqtlierefore' be realized that by: means of the: aforedescribed" invention, as the I recorder movesmver the map: of theradiorange station tlieaA' andLNsignaIsheard by the student in the trainer v will be automatically varied in si ulation of th'e'varying of the real signals interceptedby a vnavigator;.ifz" the plane were making the actual one of said sectors andanelectrical connection, betweenrsaid additional. metallic member and one.

ofisaidsectors charged in a difl'erentlcode pattern. I v I from the selected sector.

I 2.111 adevice for teaching aircraft navigation or thelike by means of 'radiorang'e signals, means I v for simulating the phenomenon of multiple courses 'of'actualradio ranges, saidmeans comprising two pairs of metallic sectorssha'pedand positioned relative to one another like the quadrants of a real, radio range station, means for edge, of. aselected. one. of said sectors, and an electrical. connection between, said additional charging. each painofl said'metallic sectors] in different predetermined code patterns simulating thecode, patternofthesignal field of a real radio range, an. additiona1. metallic. member insulated from andpl'acedcadjacent theface and near-the metallicrmember and-one of said sectors charged in a difierent code, pattern from the selected secton 3. In a device for.teachingaircrait navigation or. the like. bysmeanshcf. radio range signals,

flight being simulatedby the apparatus herein described: Alllfof the mentioned as well as other objects .of theinventionare'accomplished by the invention.

The -foregoing being but a preferred embodi ment of myinvention, and inasmuch as numerous changes-may be made in the cionsmlction thereof Without departing from the spirit, I limit myself I only by tliefollowing-claims; V

11 In a device for teachingaircraft navigation or'the like bymeans of 'radio range signals, means for" simulating the phenomenon of multiple courses of' actua'l'radio ranges, said meanscomprising two pairs of metallic sectors shaped and positioned relative to'one another like the quadrants: of a real radio range station,- means for charging each pair: of said metallic sectors in different-- predetermined code patterns simulating K the code pattern of 'the=signalfield ofa real radio range, an additional metallic member insulated fromand placed adjacent the face of a selected;

meansior simulating the phenomenon of bent equi signal; zones, said means comprising. two

pairs of metallic sectors; shaped and positioned relative. to-one. another. like the quadrants ofa real radio. rangestation, alportionof ,oneedge ofrone of. said sectors, protruding toward the adjacentedge of. an adjacent sector-which in turn is. formedngenerally. complementary to said protrusiomand means for: charging each pair of said metallic sectors in different predetermined code patterns simulating the code pattern of the signal fieldof a realradio range.

' GREGOR L. LANG.

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UNITED STATES. PATENTS Number Date 387,357 Stubblefield May 12, 1908 1,610,692. Logwood' Dec. 14, 1926 1,825,462,: Link" Sept; 29, 1931 2,0641 640 Bossart Dec. 15, 1936 2,09%);7' Link' Nov. 23, 1 937 2,110.;369 Grazia? Mar. 15, 1938 2,119,083 Linkr May 31, 1938 2,179,663 Link: Nov. 14, 1939 2,326,764? Crane" Aug. 17, 1943 following references are of record in the 

